1. Field
The present disclosure relates generally to aircraft and, in particular, to control systems in aircraft. Still more particularly, the present disclosure relates to a method and apparatus for a wingtip control system.
2. Background
In designing and operating aircraft, it is desirable to provide aircraft configurations that yield reduced fuel burn by making components within the aircraft more aerodynamic. In particular, aircraft configurations with increased fuel efficiency are ever more important as fuel costs continue to increase. Designing more fuel efficient aircraft configurations may be achieved by using airfoil structures to reduce drag during various phases of flight.
In this illustrative example, an “airfoil structure” is a structure configured to produce an aerodynamic force on an aircraft when the aircraft moves. Examples of airfoil structures for aircraft include wingtips, wings, stabilizers, airbrakes, control surfaces, rudders, flaps, spoilers, ailerons, slats, and other suitable structures.
These airfoil structures may be attached to the aircraft and, in some cases, activated by a control system to move as desired. In other cases, these airfoil structures may be stationary structures that do not move relative to other components in the aircraft.
The control and operation of moveable airfoil structures in aircraft provide various design and operation challenges for pilots and aircraft manufacturers. For example, aircraft aerodynamic drag and fuel burn are generally reduced as the wingspan of the aircraft increases. Often, however, taxiway spacing, the distance between buildings, and gate locations for airports may not provide adequate spacing for aircraft with longer wingspans.
Some attempts have been made to improve aircraft wing efficiency without adding a fixed and permanent amount of wingspan. For example, moveable airfoil structures have been used. In particular, moveable wingtips can be used to extend wingspan during takeoff and flight to improve aircraft fuel efficiency. These moveable wingtips can then be configured for reduced wingspan for operation on the ground to improve ground obstacle clearance.
These moveable wingtips may be referred to as folding wingtips configured to fold and extend in response to a command from a control system. In this illustrative example, the terms fold and extend are used for the movements to reduce and increase wingspan, respectively.
The movement to configure the wingtips for reduced wingspan may involve a system that folds the wingtips to a vertical position, a system that folds the wingtips horizontally in a forward or rearward direction, or a system that retracts the wingtips into the fixed portion of the wings.
Control systems for moveable airfoil structures may be operated by flight crew to move the airfoil structures from a deployed position to an undeployed position during various phases of flight and/or during ground operation. In some cases, however, the control systems for moving airfoil structures may be more cumbersome than desired and may involve more flight crew intervention than desired. For instance, when operating a wingtip, the flight crew may have to physically move a control on the flight deck from one position to another position at a specified point in time. In some cases, however, the operational requirements for the flight crew to make a control input to move the wingtips may occur at a phase of flight where workload and distractions may prevent the flight crew from reliably and effectively operating the system as desired.
Further, the control for the wingtip may not be as intuitive to operate as desired. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.